EDINBURGH -- With the United Kingdom officially out of the European Union, Scotland is left with a decision that could rewrite its own history: stay or leave.

Despite voting overwhelmingly against Brexit in 2016, Scotland is being forced to make the split along with England, Wales and Northern Ireland. An 11-month transition period is now underway as the U.K. negotiates new trade deals and figures out its next steps.

But Scotland's First Minister Nicola Sturgeon is leading the charge to hold a new referendum in 2020 that would test public support for Scotland’s separation from the U.K. and pit her government against the architect of Brexit, British Prime Minister Boris Johnson.

“A new independence referendum will put the decision about the best path for Scotland into our own hands. And there is a cast-iron mandate from both the public and the Scottish parliament for that referendum,” Sturgeon said at a press conference Friday morning.

Earlier this week Scotland’s pro-independence government voted in favour of holding a referendum. But whether or not Scotland could formally split from the U.K. remains far from certain. Johnson has said his government would not approve such a referendum – an official step required for Scotland’s vote to be considered binding.

Sturgeon is urging Johnson to reconsider his position, saying Scottish voters want a referendum that is “legal and legitimate.”

“It must demonstrate that there is majority support for independence, and it’s legality must be beyond a doubt. Otherwise the outcome – even successful – would not be recognized by our countries,” she said.

Scottish voters are deeply divided over the issue, but the public desire to separate appears to be growing. A recent YouGov survey found that 51 per cent of Scots agree with breaking up with the U.K. with 49 per cent opposed. Those results mark the first time since 2015 that separatists led non-separatists in such a poll.

AN UNCERTAIN FUTURE

The proposition has dredged up memories of Scotland’s 2014 referendum. In that vote, 55.3 per cent voted against separation and 44.7 per cent in favour.

Johnson cited the 2014 referendum in his public dismissal of a 2020 referendum, saying that Scotland already settled the issue six years ago. But Sturgeon and her supporters say Brexit wasn’t on the table back then, and that today’s circumstances are much different.

In Edinburgh, hundreds of protesters waving Scottish and EU flags gathered to express sadness over the move. Cities across the country held similar candlelit vigils.

In Brussels, British flags were quietly taken down from many EU buildings.

Sentiment was more mixed in London, a city home to more than 1 million EU citizens. Some celebrated the move as the beginning of a new independent Britain. Others expressed sadness about the loss of their European identities.

For Rob Carpenter, a lawyer from Prince George, B.C. who moved to Edinburgh to open a distillery, uncertainty around Scotland’s future has thrown a wrench into his plans. Brexit means that he could face new trade barriers when selling his products abroad.

“We are a start-up. We only opened in July of last year. We are new on the scene and there are a lot of things to stay awake about,” he told CTV News.

“The only thing that’s certain is uncertainty.”